Superhydrophobic and flame-retardant alginate fabrics prepared through a one-step dip-coating surface-treatment

Developing flame-retardant, environment-friendly, sustainable functional textiles is highly desirable. Alginate fibers, typically as the calcium alginate, whose raw material is extracted from natural brown seaweed, possess excellent intrinsic flame retardancy, biocompatibility, and hydrophilicity. To overcome the problem of water-absorption-induced deformation of alginate fibers, superhydrophobic alginate fabrics were prepared by a one-step dip-coating process in hexadecyltrimethoxysilane (HDTMS) alcosol. Alginate fabrics treated with 3 wt% HDTMS alcosol exhibited excellent water repellence with an average contact angle of 158.2° and a sliding angle less than 10°. The surface morphology and chemical composition of alginate textiles treated with various HDTMS concentrations were thoroughly characterized. The mechanism of the one-step dip-coating strategy was explored. Superhydrophobic surface treatment improves the deformation resistance of alginate fabrics in water, which reveals no obvious change for 7 days with a swelling absorbency of 124.1%. Salt resistance of treated alginate fabrics was also enhanced. Due to the intrinsic flame retardancy of calcium alginate, the treated alginate fabrics possessed outstanding fire-proof behaviour with a limiting oxygen index value of 28.0. Notably, a decorative flower fabricated from treated fabrics showed good water resistance and flame retardancy, which broadens the application of alginate textile in the field of environment-friendly flame-retardant functional textiles. Graphic abstract